#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
#    Code base of Animesh Sharma [ sharma.animesh@gmail.com ]


$t=shift @ARGV;
chomp $t;
$f1= fact($t);
$f2= factorial($t);
sub fact {
	my $p=shift @_;
	return undef if $p < 0;
	return 1 if $p == 0;
	return ($p * fact($p -1) );
} 
sub factorial {
    my $number = shift @_;
    return undef if $number < 0; # illegal value
    return 1 if $number == 0;

    return( $number * factorial($number -1) );
}
print "$t \t $f1\n\t $f2";